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Getting FI Code C46 / Tachometer Malfunctioning

2K views 11 replies 5 participants last post by  ChampC 
#1 ·
Just gott my ECU and Wiring harness replaced (result of a botched PCV install), bike has been running fairly well, however on my way home I noticed I had another FI Light, accompanied by my tachometer acting really freaky. Got home and tested it, at first it was the _C00 which means I need to adjust my TPS, but that only popped up cause I shut the bike off. I wanted to double check the code again after riding today, so I did and it's the C46 code.

Per the manual C46 points to a circuit malfunction, specifically the Exhaust Control Valve Actuator. With a new ECU and Wiring harness put in, I figured maybe it's unplugged? The wiring harness and ECU both came off a 6k miled K7 750, and that bike ran fine with it prior to installing it on mine, so I don't see how it could have a short already..

And with the tachometer issue. It just whacks out after any random amount of RPM's. The weird thing is, when I first turn on the ignition, it goes from top to bottom perfectly, it only seems to mess up when I'm on the throttle. I went ahead and attached a video I made of the issue. Could these issues by chance be correlated?

 
#9 ·
Yes, a friend with the same bike, that's what I had in mind. Perhaps "spare" was not the best of words.

I'm not sure it's the dash either, but the CKP sensor (and the CMP for that matter), which supplies engine speed information, is only connected to the ECU, not the dashes, so the ECU has to supply the dash with that information. I don't have a manual handy right now to double-check, but I doubt the ECU has a separate connection for the tach signal, since it relays information to the dash via the serial data line. That information includes coolant temperature, so, since that works fine (and you don't get 'CHEC') while the tach misbehaves, it's not the connection. Unless there's a separate line I'm missing, the problem can then only be inside the dash (some internal broken connection) or with the ECU, if it sends bogus information. The latter, though possible, is unlikely I think, as I can't think what would cause the ECU to send only partly corrupted serial data, except for a problem with the CKP sensor, which would cause running problems.
 
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